Introduction
In construction projects, delivering work on time is crucial, but often delays or changes in the project’s scope lead to a need for speeding up the process. Schedule compression refers to techniques used to shorten the project schedule without reducing its scope. This is commonly done to meet tight deadlines, overcome delays, or accommodate client requirements without compromising the quality of work. Two key techniques for schedule compression are Crashing and Fast Tracking. Understanding these techniques and their appropriate application can help project managers maintain control over timelines and deliver projects within set deadlines.
1. What is Schedule Compression?
Schedule compression involves reducing the duration of a construction project without changing its scope, often to meet a fixed deadline or recover from delays. It is a proactive strategy used when project completion is behind schedule or when there is a need to deliver the project sooner than initially planned.
Schedule compression techniques typically involve:
- Increasing resources (manpower, machinery, etc.)
- Adjusting task sequences
- Overlapping activities that are normally done in sequence
However, while these methods can help reduce the overall duration, they often come with additional costs, risks, or complexities.
2. Key Schedule Compression Techniques
There are two primary techniques for compressing a construction project’s schedule: Crashing and Fast Tracking. Each of these techniques comes with its advantages, disadvantages, and appropriate use cases.
A. Crashing
Crashing is a schedule compression technique in which additional resources (such as labor, equipment, or materials) are allocated to critical path activities in order to complete them faster. This technique focuses on reducing the duration of activities without reducing the project’s scope or quality.
How Crashing Works:
- Identify activities on the critical path (the sequence of tasks that determine the project’s overall duration).
- Add resources (e.g., more workers, additional machinery) to these critical tasks to complete them faster.
- Evaluate the cost-benefit of crashing. This technique usually increases project costs because of overtime, extra shifts, or renting more equipment.
Example of Crashing:
In a commercial building project, if the critical path includes the installation of the foundation, the project team may decide to bring in additional workers and equipment to expedite the concrete pouring and curing process. Although this reduces the schedule, it increases labor and equipment rental costs.
Benefits of Crashing:
- Shortens project duration effectively, especially for tasks that require only labor or machinery to speed up.
- Suitable when there are budget contingencies but critical time constraints.
Drawbacks of Crashing:
- Increased cost due to overtime pay, more equipment, or material surcharges.
- May lead to diminished productivity if overcrowding occurs or if workers are stretched too thin.
- Limited impact: Crashing only affects critical path tasks, so it doesn’t help with non-critical activities.
B. Fast Tracking
Fast Tracking is a schedule compression technique that involves executing project activities in parallel that are normally done sequentially. By overlapping these tasks, the project duration is reduced, though this increases the risk of rework or miscommunication.
How Fast Tracking Works:
- Identify activities that can be overlapped, even if they were initially planned to occur one after the other.
- Begin the successor task before its predecessor is fully complete, reducing the time between these activities.
- Careful coordination is required to manage dependencies and minimize risks of rework.
Example of Fast Tracking:
In a residential development, the project schedule initially sequences structural work to be completed before beginning interior electrical wiring. By using fast tracking, electrical work could start in certain sections while structural work is still ongoing, cutting the overall schedule by several weeks.
Benefits of Fast Tracking:
- No additional costs: It doesn’t require extra resources (like crashing does), making it an efficient way to shorten schedules without increasing expenses.
- Suitable for projects where cost overruns are unacceptable, but deadlines are rigid.
Drawbacks of Fast Tracking:
- Increased risk: Overlapping tasks can lead to coordination problems, quality issues, or rework, especially if predecessor tasks impact the outcome of successor tasks.
- Not always feasible: Some activities cannot be overlapped due to dependencies or safety concerns.
- Higher management demand: Requires constant monitoring and effective communication between teams.
3. Choosing the Right Schedule Compression Technique
The decision between crashing and fast tracking depends on the specific constraints of the project. Key factors to consider include:
- Budget: If the project has a flexible budget but tight deadlines, crashing may be the better option since additional resources can be brought in to meet the deadline. If the budget is strict, fast tracking may be preferred, even though it introduces more risks.
- Risks: Fast tracking often carries higher risk due to the potential for rework, while crashing generally has lower risk, though it comes with higher costs. A risk analysis should be conducted before choosing a method.
- Project Stage: Early in a project, fast tracking may be more feasible, as changes and overlaps in design and planning phases are more manageable. However, in later stages, crashing might be more suitable for quickly executing tasks that are less prone to coordination issues.
- Type of Project: Fast tracking is more feasible in repetitive or linear construction projects where certain tasks can be overlapped with minimal risk (e.g., housing developments). Crashing may be more suited to complex projects with distinct critical path activities (e.g., infrastructure projects).
4. Real-Life Application of Schedule Compression
A. Crashing Example: Expansion of a Power Plant
In the expansion of a power plant, delays in acquiring permits put the project behind schedule. The project manager used crashing by adding night shifts and hiring additional contractors to speed up construction. This increased labor costs significantly but allowed the project to meet the final completion date and avoid penalties for delay.
B. Fast Tracking Example: Airport Construction Project
During the construction of an international airport, fast tracking was used to begin runway paving while terminal foundations were still being built. This overlap shortened the overall construction timeline but required careful coordination between teams to avoid interference and ensure both parts of the project progressed without issues. Despite the risks, the project was completed ahead of schedule, saving the client millions in operational delays.
5. Challenges in Applying Schedule Compression
While schedule compression techniques like crashing and fast tracking can be effective, they also come with challenges:
- Coordination and Communication: Fast tracking requires continuous coordination between different teams to avoid overlap issues. Miscommunication can lead to rework and quality problems.
- Cost vs. Time Trade-off: Crashing is expensive and increases the cost of a project significantly. Balancing the cost with the time saved is a delicate decision for project managers.
- Risk Management: Both crashing and fast tracking come with risks. For crashing, the added resources can diminish productivity if not managed properly, while fast tracking increases the potential for mistakes and rework.
6. Conclusion
Schedule compression is a critical technique in managing construction projects that face tight deadlines or delays. Crashing and Fast Tracking are two key methods, each with its benefits, drawbacks, and appropriate use cases. Crashing shortens the schedule by adding resources at a higher cost, while fast tracking overlaps tasks to save time but increases risks. The choice between these techniques should be guided by a project’s budget, risk tolerance, and stage of progress. Properly applied, schedule compression can help ensure projects are completed on time without sacrificing quality or exceeding budgets.
